XINETD Super daemon and telnet installation configuration

The process in Linux is divided into three categories:

1 Independent Daemon Process

Most of the service's processes are independent daemons, and when they start they listen for the arrival of a request message on a socket such as: httpd (TCP/80) HTTPS (tcp/443) MySQL (tcp/3306) php (tcp/9000) SSH (TCP/22)

Independent daemons can typically display their runlevel with chkconfig--list + service Name

The standalone daemon can use the service name Start|stop|restart|status

2 Non-independent daemons

Non-independent daemons do not have a runlevel, and all non-independent daemons are controlled by the xinetd process, and these non-independent processes start xinetd as they are started;

3 Super Daemon Xinetd

Xinetd as a super daemon it can proxy those infrequently used non-independent daemons to listen on the corresponding ports, such as Telnet (TCP/23) swap (tcp/901) swap is the graphics configuration software of samba, these services are seldom used, in order to save resources, By the XINETD agent listening on the corresponding port such as swap tcp/901, once a request arrives, will first reach xinetd,xinetd and then according to the request message port number is 901 temporary start swap process, the request response is completed will continue to close the swap process, continue to let xinetd monitoring

Configuration files for all non-standalone daemons in the/etc/xinetd.d/directory

The following will be the installation and configuration of Telnet

The following operations are 192.168.139.2

[[email protected] sh]# Yum install telnet//installation Telnet Client

[[email protected] sh]# Yum install telnet-server//installation Telnet Server side

[[email protected] sh]# vim/etc/xinetd.d/telnet//Edit Telnet configuration file

# Default:on

# description:the Telnet Server serves Telnet sessions; It uses \

# unencrypted Username/password pairs for authentication.

Service Telnet

{

Flags = Reuse

Socket_type = Stream//stream is a TCP type, Datagrum is a UDP type

wait = no//no to allow two or more people to access simultaneously, yes only at the same time

Allow a man to wait

user = root//Run as Root

Server =/USR/SBIN/IN.TELNETD//process is telnetd (server) side

Log_on_failure + = USERID//

Disable = no//change Yes to No to allow Telnet service to run, yes to disable

}

[[Email protected] sh]# service xinetd start//Start xinetd

Starting xinetd: [OK]

[[email protected] sh]# chkconfig--list//You can see that the Telnet service is nearly started

XINETD Based services:

Chargen-dgram: off

Chargen-stream:off

Daytime-dgram: off

Daytime-stream:off

Discard-dgram: off

Discard-stream:off

Echo-dgram: off

Echo-stream: off

Tcpmux-server: off

Telnet: on

Time-dgram: off

[Email protected] sh]# NETSTAT-TNLP

Active Internet connections (only servers)

Proto recv-q send-q Local address Foreign address State Pid/program Name

TCP 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1386/sshd

TCP 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 1465/master

TCP 0 0::: +:::* LISTEN 1 762/httpd

TCP 0 0::: $:::* LISTEN 1386/sshd

TCP 0 0::: £ º::* LISTEN 2792/xinetd

TCP 0 0:: 1:25:::* LISTEN 1465/master

[Email protected] sh]# NETSTAT-TNLP |grep xinetd//Can see XINETD agent listening on Port 23rd

TCP 0 0::: 6575/xinetd

The following operations are 192.168.139.4

[[email protected] sh]# Yum install telnet//installation Telnet Client

[[email protected] sh]# chkconfig--add telnet//Add Telnet service to system service

[[email protected] sh]# Useradd Hadoop//Add Telnet user because Telnet is transmitted in plaintext, so root login is not allowed

[Email protected] sh]# passwd Hadoop

[[Email protected] sh]# telnet 192.168.139.2//login 192.168.139.2 Telnet_server

Trying 192.168.139.2 ...

Connected to 192.168.139.2.

Escape character is ' ^] '.

CentOS Release 6.7 (Final)

Kernel 2.6.32-573.el6.x86_64 on an x86_64

Login:hadoop

Password:

Last Login:mon Oct to 04:11:45 from www.jiamian.com

[Email protected] ~]$ ifconfig//ip 192.168.139.2

Eth0 Link encap:ethernet HWaddr 00:0c:29:1c:13:12

inet addr:192.168.139.2 bcast:192.168.139.255 mask:255.255.255.0

Inet6 ADDR:FE80::20C:29FF:FE1C:1312/64 Scope:link

Up broadcast RUNNING multicast mtu:1500 metric:1

RX packets:12937 errors:0 dropped:0 overruns:0 frame:0

TX packets:9614 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:1000

RX bytes:1427826 (1.3 MiB) TX bytes:1347748 (1.2 mib)

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XINETD Super daemon and telnet installation configuration